Conduit is a tube that electrical wires are run through. Conduit protects the wire from damage. The most common type of conduit is called electrical metallic tubing (EMT). Conduit is common in commercial and industrial installations, and in garages and unfinished basements in homes. General wiring in homes is usually done with NM cable (commonly referred to by the trade name Romex), not conduit. Conduit is usually made of metal, but it can also be made of plastic.